Conventional bolt action firearms have bolt assemblies that hold cartridges in firing chambers and receivers and barrels for containing high pressures (e.g., 65,000 PSI) during firing. Bolt mechanisms often have lugs with flat bearing surfaces which engage corresponding flat load bearing surfaces of the receiver. The flat lug bearing surfaces are often perpendicular with respect to a longitudinal axis of the bolt assembly. Interaction between the sear and the firing pin often forces an aft end of the bolt upwards, thus misaligning it with respect to the receiver. Because the load bearing surfaces of the receiver and lugs are flat, misalignment of the bolt causes improper contact and/or separation between the load bearing surfaces. Although the lugs may ultimately bear against the receiver when the firearm is fired, the misalignment of the bolt may cause high stresses (e.g., stresses that cause damage to the bolt lugs and/or receiver) at contact points and excessive movement of the bolt that impairs accuracy of the firearm.
To reduce unintentional movement of the bolt, gunsmiths often lap lugs against the receiver to ensure that the lugs and receiver contact one another when the bolt is locked. The lapping process often includes applying an abrasive substance (e.g., an abrasive substance with the consistency of grease) to bearing surfaces and then cycling the bolt repeatedly. With every cycle the abrasive substance wears the bearing surfaces, thereby increasing the area across which they make contact with one another. Once the bearing surfaces of the lugs adequately contact the corresponding bearing surfaces of the receiver, the lapping process is complete. Unfortunately, the lapping process is laboriously and is not suitable for multi-caliber rifles because the bearing surfaces of the receiver are uniquely matched to the bearing surfaces of the lugs. The lapping process establishes the bolt and the receiver as a matched pair only after the lapping process has been completed. In order for additional bolts (e.g., different caliber bolts) to properly bear against the receiver, the lugs of each bolt must be iteratively lapped against the receiver to slightly alter the receiver with each iteration. This process must be repeated until the bearing surfaces of the receiver and each of the bolts converge upon a common solution. This iterative process is considerably more laborious than lapping a single bolt against a receiver and produces unique receiver bearing surfaces. As a result, bolt actions that require lapping do not support bolt interchangeability without considerable difficulty and are therefore not well suited for multi-caliber rifles.
Bolt action rifles are configured for either right-handed or left-handed operation. A bolt handle can be positioned on the right side of the firearm for right-handed operation or positioned on the left side of the firearm for left-handed operation. Unfortunately, complicated tools and additional components are needed to change a conventional firearm from a right- or left-handed configuration to a left- or right-handed configuration.